Electric short wave thermionic valve generator



.April 17, 1.934.

ELECTRIC SHORT WAVE THERMION I C VALVE GENERATOR Filed- Jan. 13. 1 933E. c. s. MEGAW 1,955,011

Patented Apr. 17, 1934 UNITED STATES" PATENT- OFFICE ELECTRIC SHORT WAVETHERMIONIC VALVE GENERATOR Eric Christopher Stanley Megaw, Chelsea,London, England, assignor to The M-O Valve I Company Limited, London,England Application January 13,

1933, Serial No. 651,570

In Great Britain January 21,1932 6 Claims. (01. 250-275) This inventionrelates to valve generators of short electrical waves enclosed in sealedenvelopes. By short waves are meant those of wave length less than 3metres.

5 A generator of short waves is usually connected to a circuit tuned tothe frequency of the waves. If this circuit is placed outside theenvelope of the generator, it is often difiicult to make the circuitsmall enough to have the necessary high frequency, because the leadsfrom the interior to the exterior form part of the circuit; furthertrouble arises from the capacity between the leads where they passthrough the envelope.

According'to the invention a valve generatorof short electric wavescomprises a tuned circuit enclosed within its envelope, the frequency ofwhich can be varied without opening the envelope. One method of carryingthe invention into effect will now be described with reference to theaccompanying drawing which shows a generator constructed in accordancewith the invention.

The valve generator is of the kind in which the anode consists of twoparts and a magnetic field.

is maintained between the anode and the cathode by an electromagnet, thecylindrical pole pieces 10 of which are indicated'onthe drawing, theaxes of the pole pieces being substantially in line with the filament.

them. 3, 3' are leads to the two parts of the anode, sealed throughthefenvelope 4. Within the envelope the" leads have the form of asubstantially parallel pair of straight wires which are divided into twosections 5, 5' and 6, 6 by the movable bridge piece .of metal 7. Thisbridge piece does notrest on the wires, but is supported out of contactwith them on the glass fork 8,

sealed to the wall of the vessel, which must lie;

0 during operation approximately in a' horizontal plane.- The two prongsof the fork 8 are parallel to the wires and are provided with pairs ofcorresponding notches 9, in one of which the bridge piece 7 rests; itcan be moved from one pair of 4 corresponding notches to another bytilting the vessel, and the length of the be varied. 4 a

The tuned circuit consists of the anode segments '1, 1', the parts 5, 5'of the anode leads 5 attached to them and the bridgepiece '7; thecapacity between the bridge piece and the wires provides part of thecapacity of the circuit and at the same time couples the tuned circuitto the output circuit consisting ofthe parts 6, 6 of the section 5, 5'can thus anode leads and any apparatus connected to them A 1, 1' are thetwo parts of the. anode; 2 the incandescent cathode enclosed by changed.

I claim:---

1. A valve generatorof short electric waves including in combination ina sealedenvelope an electrode adapted to act as anode, an electrodeadapted to act as cathode, a tuned circuit, and means within. theenvelope forvarying the frequency of said tuned circuit without openingthe envelope.

2. A valve generator of short electric waves in-- cluding in combinationin a sealed envelope an electrode adapted to'act as anode and dividedinto a plurality of parts, an electrode adapted to act as cathodesurrounded by the said parts of the said divided anode, a timed circuit,and means within the envelope for varying the frequency of said tunedcircuit without opening the envelope.

3. A valve generator of short electric waves including" in combinationin a sealed envelope an electrode adapted .to act as anode and-dividedinto a plurality. of parts, an electrode adapted to actas cathodesurrounded by the said parts of the said divided anode and a tunedcircuit, the frequency of which can be varied without opening theenvelope, said circuit comprising two substantially'parallel conductingmembers each at,-

tached to an electrode in the valve and amovable bridge piece mountednear but not-in contact with the said wires.

4. A valve generator of short electric waves including in combination ina sealed envelope an electrode adapted to act as anode and divided intoa plurality of parts, an electrode adapted to act as cathode surroundedby the said parts of the said divided anode-ands. tuned circuit, thefrequency of whichcan be varied'without opening the envelope, saidcircuit comprising two substantially'parallel conducting members eachattached to an electrode in the valve and a movable bridgepiece mountednear but not incontact with the said wires supported freely on notchedinsulating members.

5. Avalve generator of short electric waves including'in combination ina sealed envelope an electrode adapted to act as anode and divided intoa plurality of parts, an electrode adapted to act as cathode surroundedby the said parts of the said divided anode and a tuned circuit, thefrequency of which can be varied without opening the envelope, saidcircuit comprising two substanelectrode adapted to act as anode anddivided into a plurality of parts, an electrode adapted to act ascathode surrounded by the said parts of the said divided anode and atuned circuit, the

'frequency of which can be varied without opening the envelope, saidcircuit comprising two substantially parallel conducting members eachattached to an electrode in the valve and a movable bridge piece mountednear but not in contact with the said wires and supported freely onnotched insulating members and movable along the length of the said twoparallel conducting members, from one pair of notches to another in thesaid notched insulating members by a suitable movement of the wholegenerator and means for maintaining a magnetic field between the saidparts of the said divided anode and the said cathode. ERIC CHRISTOPHERSTALLEY MEGAW.

